This question is interesting because it can be taken two different ways. Taken one way, we could be looking at whether Christians should be grumpy people. Taken another way, we could be looking at whether Christians are sometimes, in fact, grumpy people. I’ll look at both.
Let’s start with the second way. Is it possible for someone to be a genuine Christian and be cantankerous – or at least be perceived that way? When I read the book of Job, I don’t get the impression that Job was particularly cheerful as he suffered so horribly. Job was an Old Testament believer and even the promises which Old Testament believers embraced (pointing ahead to Christ) would give reason for cheer. Job had faith, he had hope, but yet his words portray someone who is rather deeply in the gloom.
The same is true when we read the Psalms. Many of the Psalms are laments – we hear fellow believers singing the blues. The classic example is the Dark Psalm, Psalm 88. Heman the Ezrahite penned it and he doesn’t sound at all chipper. Suitably, the last word of the psalm, both in Hebrew and in English (at least in the ESV) is darkness. Since this psalm is God’s Word, God himself is validating this experience – certainly not condemning it.
Unless we’re suffering with a big grin on our faces and a spring in our step, it would be easy for another person to conclude we’re cranky. It’s hard to suffer with a smile – when Christ suffered hell on the cross, not even he was smiling. Whether the suffering we’re experiencing is mental, physical, or circumstantial, it’s not easy to crack a smile and pretend like nothing’s wrong. So, yes, it can happen that a Christian is grumpy — or appears to be grumpy – because of the weight of the suffering they’re carrying. Let’s be careful in judging “grumpy Christians” because we don’t always know what burdens other people have on their shoulders.
But should Christians be grumpy people? Well, what would be the opposite of grumpy? We might think it to be cheerful. But with that, we limit it to our external expressions. Now there are definitely instances in Scripture where we see external expressions of happiness amongst believers in both the Old Testament and the New Testament. Certainly the gospel gives us every reason to be cheerful – this is news with a joyous sound!
However, the Bible’s picture of the ideal Christian is more complex. Joy is really what’s held out to us as the goal. Joy is a sort of deep contentment that can’t be shattered by our circumstances. It’s the sense that even if I can’t understand what’s happening to me, I know someone who loves me who does. Christian joy is a calming phenomenon – we’re able to rest knowing that, even in our suffering, we’re in the good hands of our loving Father. This is the joy the Apostle Paul exemplifies in Philippians. Though he’s in prison and it’s hard, he’s rejoicing and he encourages the Philippian Christians to do likewise.
The Bible is real about life. It doesn’t gloss over the fact that there’s suffering and hurt in this broken world. But it also holds out joy in the maelstrom. In Galatians 5, joy is described as one dimension of the fruit of the Holy Spirit. Joy comes from God, it’s grounded in the gospel, and worked in our hearts by the Holy Spirit. In a couple of places (Rom. 15:13, Col. 1:11), Paul prays for the joy of his brothers and sisters. So when we’re in a trial and the suffering is hard and joy seems to have vanished, we can and should pray for its return. We should never just settle for being grumpy. With the help of the Holy Spirit, it is possible to say when suffering, “It’s really hard for me right now. But God is still good and he still loves me – he gave his Son for me – and that gives me joy inexpressible.”